Narrowband on 庭 — a journal

Narrowband workflow (HOO/SHO)

Fri, 16 Oct 2026 00:00:00 +0000

Processing narrowband data from a monochrome camera – Ha and OIII for HOO, plus SII for SHO – from stacking to export. The stars come either from the narrowband image or from short RGB exposures.

Sh2-126 – the Gecko in Lacerta

Sun, 04 Oct 2026 00:00:00 +0000

Tucked away in the small constellation of Lacerta, the Lizard, lies a sprawling cloud of hydrogen listed as number 126 in Stewart Sharpless’s catalogue. Its glow is powered by 10 Lacertae, a hot, bluish O-type star belonging to the young stellar group Lacerta OB1. The star’s energetic ultraviolet light excites the surrounding gas, which in turn shines in the characteristic red of hydrogen. Measurements disagree on how far away the region is; most estimates fall somewhere between roughly 1,200 and 1,800 light-years. The nebula cannot be seen through the eyepiece – only long exposures bring out its structure. The shape at the head of the filaments resembles a gecko, a fitting match for its host constellation. Beyond the red bands, grey veils of dust and dark clouds absorb the light from behind.

Abell 85 — the Garlic Nebula

Sat, 26 Sep 2026 00:00:00 +0000

Abell 85, also known as CTB 1, is a large supernova remnant (SNR) located in the constellation Cassiopeia. The southern portion of the remnant’s bubble also made it into the Lynds Bright Nebula catalog as LBN 576. Originally catalogued by George Abell as a planetary nebula, it soon became evident that it was in fact an SNR.

In 2017, the citizen science project Einstein@Home — which normally analyzes gravitational-wave data from the LIGO detector — identified a pulsar within Abell 85: PSR J0002+6216, now known as the “Cannonball Pulsar.” Travelling at over 1,100 km/s, it’s one of the fastest-moving pulsars known — fast enough to eventually leave the Milky Way entirely — and it trails a radio tail roughly 13 light-years long behind it.

M 101 - Pinwheel Galaxy

Sat, 12 Sep 2026 00:00:00 +0000

The Pinwheel Galaxy is a classic spring target and is ideally placed from our location around the middle of April. These were the first images taken with the Celestron EdgeHD 8. The small spikes visible on the stars kept me puzzled for a long time, and I was convinced for a while that they were down to poor collimation. In the end it became clear to me that they were spikes caused by the dew heater. With the heater switched off, the spikes disappear. So from now on it’s dew shield only, and no heater.